best to buy a digital aerial Mattk, you will get much better reception..they can be quite expensive so it may be worthwhile for you to get a couple of quotes for a Digital Roof/Loft Aerial to be fitted and spliced nto each of your portable tellys...
Thats what Im gonna do anyway, works out cheaper for me to get a loft aerial into all the 3 bedrooms upstairs than it is to buy three seperate digital tv top aerials...just need to save up the pennies..one company that im gonna use is going to install the Roof aerial and extend it into the three rooms for �96..in total...Result...
At the moment I am using just normal run of the mill tv top aerials from Tesco for about a fiver, they are really good but still dont get all the channels i should be getting. we often have to go from room to room as we get different channels in each room..
Good luck..